Add mbedtls_ecdh_can_do
All curves can currently do ECDH, but to make the API symmetric and
future-proof, add mbedtls_ecdh_can_do() to go with mbedtls_ecdsa_can_do().
diff --git a/include/mbedtls/ecdh.h b/include/mbedtls/ecdh.h
index 7f61c45..3948d7c 100644
--- a/include/mbedtls/ecdh.h
+++ b/include/mbedtls/ecdh.h
@@ -145,6 +145,15 @@
mbedtls_ecdh_context;
/**
+ * \brief Check whether a given group can be used for ECDH.
+ *
+ * \param gid The ECP group ID to check.
+ *
+ * \return \c 1 if the group can be used, \c 0 otherwise
+ */
+int mbedtls_ecdh_can_do( mbedtls_ecp_group_id gid );
+
+/**
* \brief This function generates an ECDH keypair on an elliptic
* curve.
*